Make improvements

- Introduce ualarm() function
- Make rename() report EISEMPTY on Windows
- Always raise EINVAL upon open(O_RDONLY|O_TRUNC)
- Add macro so ./configure will detect SOCK_CLOEXEC
- Fix O_TRUNC without O_CREAT not working on Windows
- Let fcntl(F_SETFL) change O_APPEND status on Windows
- Make sure pwrite() / pread() report ESPIPE on sockets
- Raise ESPIPE on Windows when pwrite() is used on pipe
- Properly compute O_APPEND CreateFile() flags on Windows
- Don't require O_DIRECTORY to open directories on Windows
- Fix more instances of Windows reporting EISDIR and ENOTDIR
- Normalize EFTYPE and EMLINK to ELOOP on NetBSD and FreeBSD
- Make unlink() / rmdir() work on read-only files on Windows
- Validate UTF-8 on Windows paths to fix bug with overlong NUL
- Always print signal name to stderr when crashing due to SIG_DFL
- Fix Windows bug where denormalized paths >260 chars didn't work
- Block signals on BSDs when thread exits before trashing its own stack

test/libc/calls/reservefd_test.c

@@ -25,6 +25,7 @@
 #include "libc/errno.h"
 #include "libc/macros.internal.h"
 #include "libc/runtime/internal.h"
+#include "libc/runtime/runtime.h"
 #include "libc/runtime/stack.h"
 #include "libc/stdio/rand.h"
 #include "libc/str/str.h"
@@ -66,13 +67,17 @@ TEST(reservefd, testGrowthOfFdsDataStructure) {
   int i, n;
   struct rlimit rlim;
   n = 1700;  // pe '2**16/40' → 1638 (likely value of g_fds.n)
-  if (!getrlimit(RLIMIT_NOFILE, &rlim)) n = MIN(n, rlim.rlim_cur - 3);
+  if (!getrlimit(RLIMIT_NOFILE, &rlim)) {
+    n = MIN(n, rlim.rlim_cur - 3);
+  } else {
+    errno = 0;
+  }
   for (i = 0; i < n; ++i) {
-    EXPECT_SYS(0, i + 3, open("/zip/usr/share/zoneinfo/UTC", O_RDONLY));
+    ASSERT_SYS(0, i + 3, open("/zip/usr/share/zoneinfo/UTC", O_RDONLY));
   }
   ASSERT_GT(g_fds.n, OPEN_MAX);
   for (i = 0; i < n; ++i) {
-    EXPECT_SYS(0, 0, close(i + 3));
+    ASSERT_SYS(0, 0, close(i + 3));
   }
 }